This project expands the PI's research on fragile X syndrome (FXS), which has focused on the development of language and other aspects of behavior in adolescents with FXS, to include the investigation of emotional well-being in mothers of these adolescents. Preliminary studies suggest that these mothers are at risk for lower levels of emotional well-being and that their well-being is related to rates of maladaptive behavior displayed by the son or daughter with FXS. These preliminary studies, however, are limited by a lack of longitudinal data necessary to establish cause-and-effect relationships, by small sample sizes that precluded inclusion of variables reflecting important characteristics of the child, the mother, and the contexts of development, and by a lack of adequate genetic characterization of the mothers. The proposed project will build on these findings and make use of the existing cohort to facilitate recruitment. Mothers and adolescents will be assessed in a short-term longitudinal study, with 2 data collection points separated by 1 year. Self-report informant report, and direction observation will be used. Mother genetic status will be determined as well. We will determine the extent to which (1) the maladaptive behaviors of the adolescent with FXS compromise maternal emotional well-being; (2) maternal emotional well-being affects the development of maladaptive behavior in the adolescent with FXS; and (3) whether the relations between maternal well-being and adolescent maladaptive behavior are moderated by maternal genetic status, adolescent gender, and family context. This project will pave the way for future, larger studies, involving representative samples of families with a more comprehensive assessment of the impacts of FXS on mothers, adolescents, and other family members and the processes by which those effects occur.